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Case studies
In this chapter, we will take a closer look at three case studies that will demonstrate that waste can be efficiently reused. The business ventures described below have demonstrated that using waste as a resource is not a complex process and can be done in a relatively inexpensive and simple manner.
Case study no.1: Intelligent reuse of biogenic waste
Case study: Agri Protein (a British-South African agricultural company – https://www.agriprotein.com/- ) uses Christof Industries industrial plants (https://www.christof.com/en/ from Graz, Austria) in Philippi, a township in Cape Town, South Africa with about 200,000 inhabitants.
The company uses biogenic waste as a food resource for fly larvae, which are processed into protein-rich animal feed and thus contribute to combating overfishing of the oceans. The larvae meal serves as a high-quality substitute for meat meal, which is still used on a massive scale in both chicken and fish farming.
In concrete terms, this means that the company collates around 250 tonnes of waste from food factories, supermarkets and restaurants every day. Various sorts of organic waste are fully recycled here. Firstly they do a quality control check and then process the waste into a suitable and safe feed substrate. It uses this waste as a resource to feed more than 8 billion black soldier flies, which buzz through tent-like hatcheries simulating a natural habitat (e.g. specific light wavelengths mimic dawn and dusk). In a neighbouring hall larvae crawl in neatly labelled shelves at 35 degrees and eat their way through their special menu: within their ten-day lifespan, they increase their weight 200-fold. After ten days, the larvae and the substrate are separated into various product streams. The flies become a biological feedstock for the production of high-quality protein or for soil preparation.
Source: https://circle-lab.com/node/3977
Around 50 tonnes of feed are produced every day this way and sold to farmers in the neighbourhood.
Lessons learnt:
Recycling food from overproduction or misproduction and not letting it rot in the landfills has a great potential and should be practiced globally. Waste is seen as a recyclable material and solutions are sought for the increasing food demand of a growing world population for a “zero waste” system.
Case study no.2: Case study Coffee brew for mushroom production
Only about 6% of the mushrooms sold in Austrian supermarkets come from Austria; the majority are imported. “Hut und Stil” initiated by Manuel Bornbaum and Florian Hofer runs workshops on mushroom cultivation based on coffee brew. A similar approach is taken by the German micro-business Chido’s Mushrooms.
Every day, Bornbaum and Hofer collect coffee grounds in plastic containers from canteens, hotels, restaurants, coffee houses, hairdressers and similar businesses by cargo bike and exchange them for empty plastic containers on site for refilling. The coffee grounds still contain many valuable nutrients, which are especially good for growing oyster mushrooms.
Source: https://pixabay.com/de/photos/austernpilze-pilze-essbare-pilze-5725948/
They empty the coffee grounds into converted mixing machines to add lime and loosening coffee husks and mushroom spores, or cereal grains such as millet or rye are “inoculated” with it and mixed well. This mixture is then put into large black plastic bags, which are sealed and labelled. These plastic bags are first placed in the “incubation room”, where the fungi are allowed to spread at the temperature of no more than 27° Celsius, i.e. the oyster mushroom is able to grow its hyphae, white, thread-like cells that form the mycelium.
About four to five weeks after filling, the plastic bags are moved to another room, the fruiting chamber – where the plastic bags are hung on metal shelves and stored in a significantly cooler place, as the fungi like it cool and damp in this phase. In order to let the mushroom fruiting bodies sprout, the plastic bags are now also perforated in some places to give it a light stimulus (two to four crosses in each of the bags). After about a week the fungi are ready for harvesting; the fungi have grown through the entire substrate with its mycelium, and have formed the so-called primordia, or pinheads.
The mushrooms are in turn delivered to the companies by the young entrepreneurs when they collect new coffee grounds, or are sold to supermarkets. Sixty kilograms of mushrooms per square metre can be harvested annually, or from about 1,000 kg of coffee grounds, about 150 kg of mushrooms can be grown. Instead of large areas and lots of water, they grow in dark, damp cellars.
With mouth guards, scalpels and disinfectants, tiny pieces are carefully cut from the previously harvested oyster mushrooms. These are placed in Petri dishes with a so-called agar nutrient solution and sealed tightly. Once everything has been sterilised, you can watch the mushroom form its little pelt – the hyphae – and clone it.
Lessons learnt:
Using coffee brew to grow mushrooms demonstrates that waste reuse can be inexpensive and easy to implement. What start-uppers need to do is invest time in developing a detailed strategy and business model and use the already available know-how to start their own businesses.
Case study no.3: Plastic waste as resource
Plastic bottle granulate in 3D
(Fleece) pullovers are made of recycled PET bottles
Source: https://pixabay.com/photos/jeans-fashion-ruptured-modern-828693/
PET plastic fibres can be processed and used in production of new new PET products [29]. These new PET products could be for example clothing items like T-shirts or athletic shoes, automotive parts like carpet fibre or upholstery, industrial strapping, sheet and film, packaging as well as bottle for food/non-food products etc. It can also be used to turn normal plastic bottles into 3D printing filament.
PET is one of the few polymers that can be recycled into the same form over and over again. In some cases, new PET granulates might be added. A producer of plastic bottles in Austria (Vöslauer) e.g. recycles 95% of their PET packaging. The PET-to-PET lifecycle of Vöslauer bottles looks like this: used PET bottles are collected via the collection system across the country. After disposal, PET bottles are sorted by colour, pressed into large bales that weigh around 250 kilograms and contain about 10,000 PET bottles, and transported to the recycling plant in Müllendorf. There, they are converted into PET flakes and PET pellets and undergo two different processes. While one plant cleans the PET flakes, the other melts them and converts them into pellets. The PET flakes and pellets are ultimately delivered to the bottle manufacturer and used in production of new bottles [30].
PET flakes and pellets can be made on a micro-level as well. The procedures needed to be implemented are the same as the ones on performed on the industrial scale. What start-ups willing to start a business of plastic reuse need to do is:
- collect water bottles
- remove any external caps or seals
- clean them properly
- vacuum seal and heat the bottles to reduce in size
- cool the bottles
- cut them into smaller chunks with a saw and a pair of scissors
- shred the pieces into tiny pieces
- dry the pieces at a temperature of 160°C for 4 hours
- feed the PET into a Next filament extruder
- The machinery needed to process plastic waste is available and relatively affordable to new businesses too. Precious Plastic, a Dutch open hardware recycling project, offers detailed solutions for other start-ups to build their own shredder, extrusion, injection, and compression machines [31].
https://3devo.com/blog/pet-recycling-bottle-filament/
Lessons learnt:
Cleaning the bottles takes a great deal of effort, as the plastic waste coming from dumps is contaminated and in many ways impure. From the legal perspective, bottle processing may be complex, as start-ups need to meet stringent regulatory requirements. What one also hast to keep in mind is that different types of plastic produce different types of filament. High-density polyethylene, found for example in shampoo bottles, is relatively easy to turn into filament, but difficult to print with, because it shrinks more than other plastics as it cools down. On the other hand, PET prints better, but is brittle, which makes it difficult to spool as filament.